Method and apparatus for cosmetically remodeling a body structure

ABSTRACT

An apparatus for ablating at least a portion of an interior of a body structure includes a catheter with a catheter interior and a port formed in a body structure of the catheter. An ablation energy delivery device is at least partially positioned in the catheter interior. The ablation energy delivery device is configured to be advanced through the port into the interior of the body structure to a selected tissue site and deliver an ablation energy to the selected site. The ablation energy delivery device is configured to be coupled to an ablation energy source. A sensor is coupled to the ablation energy source. The sensor is positionable in the interior of the body structure and measures an impedance of at least a portion of the selected tissue site. A conductive medium introduction member is coupled to a source of a conductive medium and the catheter. A feedback control means is coupled to the sensor and the conductive medium source. The feedback control means provides a controlled delivery of the conductive medium to the selected tissue site in response to a level of measured impedance. A cable coupled to the ablation energy delivery device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 08/651,800, entitled "METHOD AND APPARATUS FORTREATMENT OF AIR WAY OBSTRUCTIONS", filed May 22, 1996, and stillpending which is a continuation-in-part application of U.S. patentapplication Ser. No. 08/642,053, entitled "METHOD FOR TREATMENT OFAIRWAY OBSTRUCTIONS", filed May 3, 1996, and still pending which is acontinuation-in-part application of U.S. patent application Ser. No.08/606, 195, filed Feb. 23, 1996, now U.S. Pat. No. 5,683,360, entitled"METHOD FOR TREATMENT OF AIRWAY OBSTRUCTIONS", which is acontinuation-in-part of U.S. application Ser. No. 08/239,658, filed May9, 1994, now U.S. Pat. No. 5,456,662, entitled "METHOD FOR REDUCINGSNORING BY RF ABLATION OF THE UVULA", all incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and apparatus for reducing aninterior volume of a body structure, and more articularly to a methodand apparatus reducing a volume of the tongue and controlling animpedance through the introduction of a conductive

2. Description of Related Art

Sleep-apnea syndrome is a medical condition characterized by daytimehypersomnomulence, morning arm aches, intellectual deterioration,cardiac arrhythmias, snoring and thrashing during sleep. It is caused byfrequent episodes of apnea during the patient's sleep. The syndrome isclassically subdivided into two types. One type, termed "central sleepapnea syndrome", is characterized by repeated loss of respiratoryeffort. The second type, termed obstructive sleep apnea syndrome, ischaracterized by repeated apneic episodes during sleep resulting fromobstruction of the patient's upper airway or that portion of thepatient's respiratory tract which is cephalad to, and does not include,the larynx.

Treatment thus far includes various medical, surgical and physicalmeasures. Medical measures include the use of medications such asprotriptyline, medroxyprogesterone, acetazolamide, theophylline,nicotine and other medications in addition to avoidance of centralnervous system depressants such as sedatives or alcohol. The medicalmeasures above are sometimes helpful but are rarely completelyeffective. Further, the medications frequently have undesirable sideeffects.

Surgical interventions have included uvulopalatopharyngoplasty,tonsillectomy, surgery to correct severe retrognathia and tracheostomy.In one procedure the jaw is dislodged and pulled forward, in order togain access to the base of the tongue. These procedures may be effectivebut the risk of surgery in these patients can be prohibitive and theprocedures are often unacceptable to the patients.

Physical measures have included weight loss, nasopharyngeal airways,nasal CPAP and various tongue retaining devices used nocturnally. Thesemeasures may be partially effective but are cumbersome, uncomfortableand patients often will not continue to use these for prolonged periodsof time. Weight loss may be effective but is rarely achieved by thesepatients.

In patients with central sleep apnea syndrome, phrenic nerve ordiaphragmatic pacing has been used. Phrenic nerve or diaphragmaticpacing includes the use of electrical stimulation to regulate andcontrol the patient's diaphragm which is innervated bilaterally by thephrenic nerves to assist or support ventilation. This pacing isdisclosed in Direct Diaphragm Stimulation by J. Mugica et al. PACE vol.10 January-February 1987, Part II, Preliminary Test of a MuscularDiaphragm Pacing System on Human Patients by J. Mugica et al. fromNeurostimulation: An Overview 1985 pp. 263-279 and Electrical Activationof Respiration by Nochomovitez IEEE Eng. in Medicine and Biology; June,1993.

However, it was found that many of these patients also have some degreeof obstructive sleep apnea which worsens when the inspiratory force isaugmented by the pacer. The ventilation induced by the activation of thediaphragm also collapses the upper airway upon inspiration and draws thepatient's tongue inferiorly down the throat choking the patient. Thesepatients then require tracheostomies for adequate treatment.

A physiological laryngeal pacemaker as described in PhysiologicalLaryngeal Pacemaker by F. Kaneko et al. from Trans Am Soc Artif InternOrgans 1985 senses volume displaced by the lungs and stimulates theappropriate nerve to open the patient's glottis to treat dyspnea. Thisapparatus is not effective for treatment of sleep apnea. The apparatusproduces a signal proportional in the displaced air volume of the lungsand thereby the signal produced is too late to be used as an indicatorfor the treatment of sleep apnea. There is often no displaced air volumein sleep apnea due to obstruction.

One measure that is effective in obstructive sleep apnea istracheostomy. However, this surgical intervention carries considerablemorbidity and is aesthetically unacceptable to many patients. Othersurgical procedures include pulling the tongue as forward as possibleand surgically cutting and removing sections of the tongue and otherstructures which can close off the upper airway passage.

There is a need for a method and apparatus to overcome these problems.There is a further need for a method and apparatus to ablate a selectedsection in an interior section of the tongue and to deliver a conductivemedium to modify an impedance of the selected section during thedelivery of electromagnetic energy to the selected section.

SUMMARY OF THE INVENTION

Accordingly, an object of the invention is to provide a method andapparatus to reduce a volume of an interior of a body structure.

Another object of the invention is to provide a method and apparatus toreduce the volume of the tongue.

Still another object of the invention is to provide a method andapparatus to reduce a volume of a selected section of an interior of thetongue.

A further object of the invention is to provide a method and apparatusto reduce a volume of an interior section of the tongue and control animpedance of the interior section.

Yet another object of the invention is to provide a method and apparatusto reduce a volume of a selected section of an interior of the tonguewhile introduce a conductive medium to control impedance at the selectedsection.

These and other objects of the invention are achieved in an apparatusfor ablating at least a portion of an interior of a body structureincluding a catheter with a catheter interior and a port formed in abody structure of the catheter. An ablation energy delivery device is atleast partially positioned in the catheter interior. The ablation energydelivery device is configured to be advanced from the port into theinterior of the body structure to a selected tissue site, and deliver anablation energy to the selected site. The ablation energy deliverydevice is configured to be coupled to an ablation energy source. Asensor is coupled to the ablation energy source. The sensor ispositionable in the interior of the body structure and measures animpedance of at least a portion of the selected tissue site. Aconductive medium introduction member is coupled to a source of aconductive medium and the catheter. A feedback control means is coupledto the sensor and the conductive medium source. The feedback controlmeans provides a controlled delivery of the conductive medium to theselected tissue site in response to a level of measured impedance. Acable couples to the ablation energy delivery device.

In another embodiment of the invention, a method for reducing a volumeof a tongue provides an ablation apparatus including a source ofablation energy, an ablation energy delivery device and a conductivemedium introduction member coupled to a source of a conductive medium.At least a portion of the ablation energy delivery device is advancedinto an interior of the tongue. A sufficient amount of energy isdelivered from the energy delivery device into the interior of thetongue to debulk a selected section of the tongue without damaging ahypoglossal nerve. An impedance of the selected section of the tongue ismeasured. The conductive medium is introduced into the selected sectionof the tongue to modify the impedance.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of an ablation apparatus used with themethods of the present invention.

FIG. 2 is cross-sectional view illustrating the catheter and connectorof the ablation apparatus shown in FIG. 1.

FIG. 3 is a perspective view of the connector illustrated in FIG. 1.

FIG. 4 is a perspective view of a needle electrode associated with theablation apparatus illustrated in FIG. 1.

FIG. 5 is a perspective view of a flexible needle electrode utilizedwith the methods of the present invention.

FIG. 6 illustrates the creation of ablation zones with the ablationapparatus shown in FIG. 1.

FIG. 7 is a cross-sectional view of the tongue with the mouth closed.

FIG. 8 is a cross-sectional view of the tongue with the mouth open.

FIG. 9 is a perspective view of the tongue.

FIG. 10 is a perspective view of the dorsum of the tongue.

FIG. 11 is a cross-sectional view of the tongue.

FIG. 12 is a cross-sectional view of the tongue illustrating thelocation of the hypoglossal nerves and the creation of an ablation zone.

FIG. 13 is a cross-sectional view of the tongue illustrating a pluralityof ablation zones.

FIG. 14 is a perspective view of the ventral surface of the tongue.

FIG. 15 is a cross-sectional view of the tongue.

FIG. 16 is an open or closed loop feedback system couple one or moresensors to an energy source.

FIG. 17 is a block diagram illustrating an analog amplifier, analogmultiplexer and microprocessor used with the feedback control system.

FIG. 18 is a block diagram of a temperature/impedance feedback systemthat can be used to control a conductive medium flow rate through thecatheter of FIG. 1.

FIG. 19 is a block diagram of a temperature/impedance feedback systemthat can be used to control cooling medium flow rate through thecatheter of FIG. 1.

FIG. 20 is a three dimensional graph illustrating the percent shrinkageof the tongue following RF ablation.

FIG. 21 is a graph illustrating two-dimensional shrinkage of bovinetongue tissue with RF ablation.

FIG. 22 is a graph illustrating three-dimensional shrinkage of bovinetongue tissue due to RF ablation.

DETAILED DESCRIPTION

A method for cosmetically remodeling and debulking the tongue, uvula,soft palate, lingual tonsil and/or adenoids provides an ablationapparatus including a source of electromagnetic energy and one or moreablation source delivery devices coupled to the electromagnetic energysource. At least one ablation source delivery device is advanced into aninterior of the tongue. Sufficient electromagnetic energy is deliveredfrom the ablation source delivery device to debulk a section of thetongue without damaging the hypoglossal nerve. The ablation sourcedelivery device is then removed from the interior of the tongue. Amethod for treating airway obstructions is achieved by debulking thetongue without damaging the hypoglossal nerve. The ablation sourcedelivery device can be introduced into the tongue from the tongue's tip,ventral surface, dorsum, underneath the tongue, along the tongue'smidline, or in certain instances through the chin area. The tongue isablated (debulked) without damaging the hypoglossal nerves, resulting ina remodeling of the tongue and a cosmetic change. This is achieved bypositioning the ablation source delivery devices far enough away fromthe hypoglossal nerves so that during the delivery of electromagneticenergy to the tongue, the hypoglossal nerves are not damaged. Anothermethod for treating airway obstructions is achieved by debulking thelingual tonsil without damaging the hypoglossal nerve. These methods areused to treat sleep apnea.

Referring to FIGS. 1 and 2, an ablation apparatus 10 for cosmeticallyremodeling and debulking the tongue, lingual tonsils, uvula, soft palateand/or adenoids is illustrated. Ablation apparatus 10 can be positionedso that one or more energy delivery devices or ablation source deliverydevices 12 are introduced into an interior of the tongue through thetongue. Ablation apparatus 10 may include atraumatic intubation with orwithout visualization, provide for the delivery of oxygen oranesthetics, and can be capable of suctioning blood or other secretions.It will be appreciated that ablation apparatus 10 is used to treat avariety of different obstructions in the body where passage of gas isrestricted. One embodiment is the treatment of sleep apnea usingablation source delivery devices 12 to ablate (cell necrosis) selectedportions of the tongue, lingual tonsils and/or adenoids by the use ofresistive heating, RF, microwave, ultrasound and liquid thermal jet. Thepreferred energy source is an RF source. In this regard, ablationapparatus 10 can be used to ablate targeted masses including but notlimited to the tongue, tonsils, turbinates, soft palate tissues, hardtissue and mucosal tissue. In one embodiment, ablation apparatus 10 isused to debulk the tongue in order to increase the cross-sectional areaof the air passageway. A disinfectant medium introduction memberintroduces a disinfectant medium in the oral cavity in order to reduceinfection of the ablated body member.

Prior to debulking the tongue, a presurgical evaluation may be performedincluding a physical examination, fiberoptic pharyngoscopy,cephalometric analysis and polygraphic monitoring. The physicalexamination emphasized the evaluation of the head and neck. It alsoincludes a close examination of the nasal cavity to identify obstructingdeformities of the septum and turbinate; oropharyngeal obstruction froma long, redundant soft palate or hypertrophic tonsils; andhypopharyngeal obstruction from a prominent base of the tongue.

Debulking apparatus 10 includes a catheter 14, an optional handle 16 andone or more ablation source delivery devices 12 extending from differentports 18 formed along a longitudinal surface of catheter 14, or from adistal end of ablation source delivery device 12. Catheter 14 can be ahandpiece. An advancement device 20 may be provided. Advancement device20 can include guide tracks or tubes 23 positioned in the interior ofcatheter 14. Ablation source delivery devices 12 may be positioned inguide tracks 23 and advanced from guide tracks into the interior of thetongue.

Ablation or debulking apparatus 10 includes a catheter 14, an optionalhandle 16 and one or more ablation source delivery device 12 extendingfrom different ports 18 formed along a longitudinal surface of catheter14, or from a distal portion of ablation source delivery device 12Catheter 14 can be a handpiece. Ablation source delivery deviceadvancement device 20, also known as advancement device 20 may beprovided. Ablation source delivery device advancement device 20 caninclude guide tracks or tubes 23 positioned in the interior of catheter14. Ablation source delivery device 12 may be positioned in guide tracks23 and advanced from the guide tracks into the interior of the tongue.Cabling is coupled to ablation source delivery device 12.

Ablation source delivery device 12 may be least partially positioned inan interior of catheter 14. In one embodiment, ablation source deliverydevice 12 is advanced and retracted through a port 18 formed in anexterior surface of catheter 14. Ablation source delivery deviceadvancement and retraction device 20 advances ablation source deliverydevice 12 out of catheter 14, into an interior of a body structure andcan also provide a retraction of ablation source delivery device 12 fromthe interior of the body structure. Although the body structure can beany number of different structures, the body structure will hereafter bereferred to as the tongue. Ablation source delivery device 12 pierce anexterior surface of the tongue and are directed to an interior region ofthe tongue. Sufficient ablation energy is delivered by ablation source12 to the interior of the tongue to cause the tongue to becomesufficiently ablated and debulked. Ablation source delivery device 12can be a hollow structure that is, (i) adapted to deliver differentchemicals to a selected tongue interior ablation site (for chemicalablation) (ii) deliver alcohol or other liquids or semi-liquids toachieve ablation as well as a variety of different infusion mediums,including but not limited to saline, chemotherapy, a conductive mediumto adjust impedance at the selected tissue site and the like. Differentmodalities can be combined to achieved a desired ablation including butnot limited to RF and chemotherapy, chemical and chemotherapy. Ablationsource delivery device 12 may have a limited travel distance in thetongue. In one embodiment with RF electrodes, this is achieved with aninsulation sleeve that is in a surrounding relationship to an exteriorof an electrode. Other devices can include a structure located onablation source delivery device 12 which limits their advancement, or astructure coupled to a catheter which limits the advancement of ablationsource delivery devices 12, such as a stop and the like. One suitablefluid is an electrolytic solution. Instead of direct contact with tissueand ablation source delivery device 12 for the delivery of thermalenergy, a cooled electrolytic solution can be used to deliver thethermal energy to the tissue. The electrolytic solution may be cooled inthe range of about 30 to 55 degrees C.

Catheter 14 includes a catheter tissue interface surface 22, a coolingmedium inlet conduit 24 and a cooling medium exit conduit 26, as well asa conductive medium channel extending through an interior of catheter14. Ports 18 are formed in the exterior of catheter 14, and arepreferably formed on catheter tissue interface surface 22. Ports 18 areisolated from a cooling medium flowing through catheter 14. Coolingprovides a cooled section of catheter tissue interface surface 22 of atleast 1 to 2 cm². More preferably, the cooled section of catheter tissueinterface surface 22 is at least equal to the cross-sectional diameterof the underlying zone of ablation. In one embodiment, the cooledsection of catheter tissue interface surface 22 is at least equal to thecross-sectional diameter of the underlying zone of ablation. In anotherembodiment, the cooled section of catheter tissue interface surface 22only provides cooling to an area associated with each deployed ablationsource delivery device. The size of the cooled section of cathetertissue interface surface 22 varies for each patient. The size issufficient enough to minimize swelling of the tongue following thedelivery of electromagnetic energy. The reduction of swelling can be 50%or greater, 75% or greater, and 90% and greater. The amount of coolingprovided is sufficient to enable the patient to return home shortlyafter the debulking procedure is performed, and not run the risk ofchoking on the tongue. It has been found that by providing a sufficientlevel of cooling over a relatively large area, the amount of ablation inan interior region of the tongue is enhanced. By providing asufficiently large enough cooled section of catheter tissue interfacesurface 22, an adenomas response is minimized.

A conductive medium source is coupled to ablation source delivery device12, which is typically a needle electrode. The conductive medium channelreceives conductive medium and delivers it to the needle electrode. Thelevel of impedance is monitored, and the delivery of conductive mediumis increased or decreased depending on the measured impedance.

Handle 16 is preferably made of an insulating material. When ablationsource delivery device 12 is an electrode the electrode is made of aconductive material such as stainless steel. Additionally, the electrode12 can be made of a shaped memory metal, such as nickel titanium,commercially available from Raychem Corporation, Menlo Park, Calif. Inone embodiment, only a distal end of electrode 12 is made of the shapedmemory metal in order to effect a desired deflection. When introducedinto the oral cavity, catheter 14 can be advanced until a patient's gagresponse is initiated. Catheter 14 is then retracted back to preventpatient's gagging. The distal end of electrode 12 can be semi-curved.The distal end can have a geometry to conform to an exterior of thetongue.

In one embodiment of the invention catheter 14 is a handpiece. In thisembodiment, a separate handle 16 is not necessary. Debulking apparatus10 is used to treat an interior region of the tongue. Catheter 14 has adistal end that is sized to be positioned within an oral cavity.Ablation source delivery device 12 is at least partially positionedwithin an interior of catheter 14. Ablation source delivery device 12includes ablation delivery surface 30. Ablation source delivery device20 is coupled to ablation source delivery device 12 and calibrated toadvance ablation source delivery device 12 from catheter 14, includingbut not limited to a distal position of catheter 14, into the interiorof the tongue when catheter 14 is positioned adjacent to a surface ofthe tongue. Ablation source delivery device 12 is advanced anadvancement distance 33 from catheter 14 of sufficient length to treatthe interior region of the tongue with ablation energy and/or anablation effect without damaging the hypoglossal nerve or the surface ofthe tongue.

Catheter 14 can be malleable in order to conform to the surface of thetongue when a selected ablation target site is selected. An encapsulatedsoft metal, such as copper, or an annealed metal/plastic material can beused to form malleable catheter 14. All or a portion of catheter 14 maybe malleable or made of a shaped memory metal.

For many applications it is desirable for a distal end 14' of catheter14 to be deflectable. This can be achieved mechanically or with the useof memory metals. A steering wire, or other mechanical structure, can beattached to either the exterior or interior of distal end 14'. In oneembodiment, a deflection knob located on handle 16 is activated by thephysician causing a steering wire to tighten. This imparts a retractionof distal end 14', resulting in its deflection. It will be appreciatedthat other mechanical devices can be used in place of the steering wire.The deflection may be desirable for tissue sites with difficult access.

Controlled volumetric reduction of the tongue, under feedback control isused to achieve an effective opening in the airway passage. A variety ofdifferent pain killing medicaments, including but not limited toXylocaine, may be used. A digital ultrasonic measurement system can beused. The ultrasound measurement quantifies biological shape changes,provides ultrasonic transmission and reception, uses piezoelectrictransducers (crystals) and provides time of flight data.

A disinfectant medium introduction member 21 may also be introduced intothe oral cavity. The disinfectant medium can be introduced prior toablation, during ablation and/or after the ablation. It can be deliveredcontinuously. The level of disinfection of the oral cavity is selectableas the volume of the oral cavity that is disinfected. The degree ofdisinfection varies. Disinfection is provided to reduce infection of theablated body structure. Disinfectant medium introduction member 21 canbe introduced before, after or during the introduction of ablationapparatus 10 into the oral cavity. Additionally, disinfectant mediumintroduction member 21 can be removed at the same time or at a differenttime that ablation apparatus 10 is removed from the oral cavity.

Disinfectant medium introduction member 21 can be included in ablationapparatus 10, in an interior of catheter 14 or at an exterior ofcatheter 14, and may be an introducer with a lumen configured tointroduce a disinfectant agent from a disinfectant agent source 23 intoall or a selected portion of the oral cavity. Disinfectant mediumintroduction member 21 can be capable of movement within the oral cavityin order to provide for disinfection of all or only a portion of theoral cavity. For purposes of this disclosure, the oral cavity is thatbody internal environment where infectious germs may be introduced intothe ablated tongue, soft tissue structure, and the like. Disinfectantmedium introduction member 21 may be slideably positioned in catheter 14or at its exterior. Alternatively, disinfectant medium introductionmember 21 can be an optical fiber coupled to a light energy source,including but not limited to a UV source 25. The optical fiber can alsobe slideably be positioned in the oral cavity. The optical fiber isconfigured to provide for the selective disinfection of all or only aportion of the oral cavity and can have a variety of different distalends to achieve this purpose.

Suitable disinfectant agents include but are not limited to Peridex, anoral rinse containing 0.12% chlorhexidine glucinate(1,1'-hexanethylenebis 5-(p-chlorophenyl) biganide}di-D-gluconate in abase containing water, 11.6% alcohol, glycerin, PEG 40 sorbitanarisoterate, flavor, dosium saccharin, and FD&C Blue No. 1.

It will be appreciated that a variety of different disinfectants can beemployed, including other electromagnetic wavelengths, and variouschemical compositions.

Ablation source delivery devices 12 are at least partially positioned inan interior of catheter 14. Each ablation source delivery device 12 isadvanced and retracted through a port 18 formed in an exterior surfaceof catheter 14. Advancement and retraction device advances ablationsource delivery devices 12 out of catheter 14, into an interior of abody structure and retracted back into catheter 14. Ablation sourcedelivery devices 12 pierce an exterior surface of the tongue and aredirected to an interior region of the tongue. Sufficient electromagneticenergy is delivered by ablation source delivery devices 12 to theinterior of the tongue to cause the tongue to become sufficientlyablated and debulked. Ablation source delivery devices 12 can be hollowto receive a variety of different infusion mediums, including but notlimited to saline. Ablation source delivery devices 12 may be limited inthe distance that they can be advanced into the tongue. This is achievedwith an insulation sleeve, a structure located on ablation sourcedelivery devices 12 which limits their advancement, or a structurecoupled to catheter which limits the advancement of ablation sourcedelivery devices 12, such as a stop and the like.

The disinfectant medium can be introduced prior to ablation, duringablation and/or after the ablation. It can be delivered continuously.The level of disinfection of the oral cavity is selectable as is thevolume of the oral cavity that is disinfected. The degree ofdisinfection varies. Disinfection is provided to reduce infection of theablated body structure.

An ablation delivery surface, such as an electromagnetic energy deliverysurface 30 of electrode 12 can be adjusted by inclusion of an adjustableor non-adjustable insulation sleeve 32 (FIGS. 3, 4, and 5). Insulationsleeve 32 can be advanced and retracted along the exterior surface ofelectrode 12 in order to increase or decrease the length of theelectromagnetic energy delivery surface 30. Insulation sleeve 32 can bemade of a variety of materials including but not limited to nylon,polyimides, other thermoplastics and the like. The size ofelectromagnetic energy delivery surface 30 can be varied by othermethods including but not limited to creating a segmented electrode witha plurality of electrodes that are capable of being multiplexed andindividually activated, and the like.

Referring specifically to FIG. 4, ablation source delivery device 12 hasan advancement length 33 that extends from an exterior surface ofcatheter 14 and is directed into the interior of the tongue. Advancementlength 33 is sufficient to position ablation delivery surface 30 at aselected tissue site in the interior of the tongue. Ablation deliverysurface 30 is of sufficient length so that the ablation effect isdelivered to the selected tissue site, create a desired level ofablation at the selected tissue site without causing damage to thehypoglossal nerve. Ablation delivery surface 30 is not always at thedistal end of ablation source delivery device 12. Insulation 32 can alsobe positioned at the distal end of ablation source delivery device 12.In this embodiment, ablation delivery surface 30 does not extend to thedistal end of ablation source delivery device 12. However, ablationdelivery surface 30 still delivers a sufficient ablation effect tocreate a desired level of cell necrosis in the interior of the tongue atthe selected tissue site without damaging the hypoglossal nerve and/ordamage to the surface of the tongue. Additionally, only one side or aportion of a side of ablation source delivery device 12 can beinsulated. This also provides for an ablation source delivery device 12which can be positioned throughout the tongue, including adjacent to ahypoglossal nerve. Where ablation source delivery device 12 is adjacentto the hypoglossal nerve, ablation source delivery device 12 isinsulated.

In one embodiment, advancement length 33 is 1.2 to 1.5 cm, and thelength of ablation delivery surface 30 is 5 to 10 mm, more preferablyabout 8 min.

In another embodiment, advancement length 33 is insufficient to reachthe hypoglossal nerve when introduced through any of the tonguesurfaces, particularly the dorsum of the tongue.

Advancement device 20 is configured to advance at least a portion ofeach ablation source delivery device 12 to a placement position in theinterior of the tongue. Advancement device 20 can also be configured toretract each ablation source delivery device 12. At the placementposition, ablation delivery surface delivers sufficient ablation energyand/or effect to reduce a volume of the selected site without damaging ahypoglossal nerve and/or a surface of the tongue. In one embodiment,ablation source delivery device advancement and retraction device 20,with or without guide tracks 23, directs the delivery of ablation sourcedelivery device 12 from catheter 14 into the interior of the tongue atan angle of 60 to 90 degrees relative to a longitudinal axis of catheter14, and preferably about 70 degrees.

In certain embodiments, ablation source delivery device 12 has ageometric shape, including but not limited to a curved configurationthat includes one or more insulated surfaces, either partially insulatedon one side, at a proximal end, at a distal end, and the like, that isconfigured to reduce the volume of the selected tissue site withoutdamaging a hypoglossal nerve. In one embodiment, ablation sourcedelivery device 12 is introduced through any tongue surface and isconfigured so that a section of ablation source delivery device 12 whichmay be positioned close to the hypoglossal nerve is provided withinsulation 32. As previously noted, insulation 32 can be positioned atdifferent sites of ablation source delivery device 12.

Handle 16 can comprise a connector 34 coupled to retraction andadvancement device 20. Connector 34 provides a coupling of ablationsource delivery devices 12 to power, feedback control, temperatureand/or imaging systems. An RF/temperature control block 36 can beincluded.

In one embodiment, the physician moves retraction and advancement device20 in a direction toward a distal end of connector 34. Ablation sourcedelivery devices 12 can be spring loaded. When retraction andadvancement device 20 is moved back, springs cause selected ablationsource delivery devices 12 to advance out of catheter 14.

One or more cables 38 couple ablation source delivery devices 12 to anelectromagnetic energy source 40. A variety of energy sources 40 can beused with the present invention to transfer electromagnetic energy tothe interior of a body structure, including but not limited to RF,microwave, ultrasound, coherent light and thermal transfer. Preferably,energy source 40 is a RF generator. When a RF energy source is used, thephysician can activate RF energy source 40 by the use of a foot switch(not shown) coupled to RF energy source 40.

One or more sensors 42 may be positioned on an interior or exteriorsurface of ablation source delivery device 12, insulation sleeve 32, orbe independently inserted into the interior of the body structure.Sensors 42 permit accurate measurement of temperature at a tissue sitein order to determine, (i) the extent of ablation, (ii) the amount ofablation, (iii) whether or not further ablation is needed, and (iv) theboundary or periphery of the ablated geometry. Further, sensors 42prevent non-targeted tissue from being destroyed or ablated.

Sensors 42 are of conventional design, including but not limited tothermistors, thermocouples, resistive wires, and the like. Suitablesensors 42 include a T type thermocouple with copper constantene, Jtype, E type, K type, fiber optics, resistive wires, thermocouple IRdetectors, and the like. It will be appreciated that sensors 42 need notbe thermal sensors.

Sensors 42 measure temperature and/or impedance to permit ablationmonitoring. This reduces damage to tissue surrounding the targetedablation mass. By monitoring the temperature at various points withinthe interior of the body structure the periphery of ablation can beascertained and it is possible to determine when the ablation iscompleted. If at any time sensor 42 determines that a desired ablationtemperature is exceeded, then an appropriate feedback signal is receivedat energy source 40 and the amount of energy delivered is regulated.

Ablation or debulking apparatus 10 can include visualization capabilityincluding but not limited to a viewing scope, an expanded eyepiece,fiber optics, video imaging, and the like.

Additionally, ultrasound imaging can be used to position the ablationsource delivery devices 12 and/or determine the amount of ablation. Oneor more ultrasound transducers 44 can be positioned in or on ablationsource delivery device 12, catheter 14, or on a separate device. Animaging probe may also be used internally or externally to the selectedtissue site. A suitable imaging probe is Model 21362, manufactured andsold by Hewlett Packard Company. Each ultrasound transducer 44 iscoupled to an ultrasound source (not shown). With reference now to FIG.6 catheter 14 is shown as being introduced into the oral cavity andmultiple RF ablation source delivery devices 12 are advanced into theinterior of the tongue creating different ablation zones 46. Using RF,ablation apparatus 10 can be operated in either bipolar or monopolarmodes. In FIG. 6, electrodes 12 are operated in the bipolar mode,creating sufficient ablation zones 46 to debulk the tongue withoutaffecting the hypoglossal nerves and creating a larger airway passage.With this debulking, the back of the tongue moves in a forward directionaway from the air passageway. The result is an increase in thecross-sectional diameter of the air passageway.

Using RF, ablation apparatus 10 can also be operated in the monopolarmode. A groundpad can be positioned in a convenient place such as underthe chin. A single electrode 12 is positioned in the tongue to create afirst ablation zone 46. Electrode 12 can then be retracted from theinterior of the tongue, catheter 14 moved, and electrode 12 is thenadvanced from catheter 14 into another interior section of the tongue. Asecond ablation zone 46 is created. This procedure can be completed anynumber of times to form different ablation regions in the interior ofthe tongue. More than one electrode 12 can be introduced into the tongueand operated in the bipolar mode. Electrodes 12 are then repositioned inthe interior of the tongue any number of times to create a plurality ofconnecting or non-connecting ablation zones 46.

Referring now to FIGS. 7 through 15, various anatomical views of thetongue and other structures are illustrated. The different anatomicalstructures are as follows: the genioglossus muscle, or body of thetongue is denoted as 48; the geniohyoid muscle is 50; the mylohyoidmuscle is 52; the hyoid bone is 54; the tip of the tongue is 56; theventral surface of the tongue is denoted as 58; the dorsum of the tongueis denoted as 60; the inferior dorsal of the tongue is denoted as 62;the reflex of the vallecula is 64; the lingual follicles are denoted as66; the uvula is 68; the adenoid area is 70; the lateral border of thetongue is 72; the circumvallate papilla is 74, the palatine tonsil is76; the pharynx is 78; the redundant pharyngeal tissue is 80; theforamen cecum is 82; the hypoglossal nerve is 84, and the lingual frenumof the tongue is 86.

Dorsum 60 is divided into an anterior 2/3 and inferior dorsal 62. Thedelineation is determined by circumvallate papilla 74 and foramen cecum82. Inferior dorsal 62 is the dorsal surface inferior to circumvallatepapilla 74 and superior reflex of the vallecula 64. Reflex of thevallecula 64 is the deepest portion of the surface of the tonguecontiguous with the epiglottis. Lingual follicles 66 comprise thelingual tonsil.

Catheter 14 can be introduced through the nose or through the oralcavity. Electrodes 12 can be inserted into an interior of the tonguethrough dorsum surface 60, inferior dorsal surface 62, ventral surface58, tip 56 or geniohyoid muscle 50. Additionally, electrodes may beintroduced into an interior of lingual follicles 66 and into adenoidarea 70. Once electrodes 12 are positioned, insulation sleeve 32 menergydelivery s provided a desired electromagnetic energy delivery surface 30for each electrode 12.

Ablation zones 46 are created without damaging hypoglossal nerves 84.This creates a larger air way passage and provides a treatment for sleepapnea.

In all instances, the positioning of electrodes 12, as well as thecreation of ablation zones 46 is such that hypoglossal nerves 84 are notablated or damaged. The ability to swallow and speak is not impaired.

In one embodiment, RF electrode 12 are placed on the dorsum surface ofthe tongue. The first electrode is positioned 0.5 cm proximal to thecircumvallate papilla. The other electrodes are spaced 1.6 cm apart andare 1 cm off a central axis of the tongue. In one embodiment, 465 MHz RFwas applied. The temperature at the distal end of electrode 12 was about100 degrees C. The temperature at the distal end of the insulationsleeve 32 was about 60 degrees C. In another embodiment, the temperatureat the distal end of insulation sleeve 32 was 43 degrees C. and above.RF energy can be applied as short duration pulses with low frequency RF.Precise targeting of a desired ablation site is achieved. One or moreelectrodes 12 may be used to create volumetric three-dimensionalablation. A variety of ablation geometries are possible, including butnot limited to rectilinear, polyhedral, redetermined shapes, symmetricaland non-symmetrical.

Referring now to FIGS. 16 and 17 an open or closed loop feedback systemcouples sensors 42 to energy source 40. The temperature of the tissue,or of electrode 12 is monitored, and the output power of energy source40 adjusted accordingly. Additionally, the level of disinfection in theoral cavity can be monitored. The physician can, if desired, overridethe closed or open loop system. A microprocessor can be included andincorporated in the closed or open loop system to switch power on andoff, as well as modulate the power. The closed loop system utilizes amicroprocessor 88 to serve as a controller, watch the temperature,adjust the RF power, look at the result, refeed the result, and thenmodulate the power.

With the use of sensors 42 and the feedback control system a tissueadjacent to RF electrodes 12 can be maintained at a desired temperaturefor a selected period of time without impeding out. Each RF electrode 12is connected to resources which generate an independent output for eachRF electrode 12. An output maintains a selected energy at RF electrodes12 for a selected length of time.

When an RF electrode is used, current delivered through RF electrodes 12is measured by current sensor 90. Voltage is measured by voltage sensor92. Impedance and power are then calculated at power and impedancecalculation device 94. These values can then be displayed at userinterface and display 96. Signals representative of power and impedancevalues are received by a controller 98.

A control signal is generated by controller 98 that is proportional tothe difference between an actual measured value, and a desired value.The control signal is used by power circuits 100 to adjust the poweroutput in an appropriate amount in order to maintain the desired powerdelivered at respective RF electrodes 12.

In a similar manner, temperatures detected at sensors 42 providefeedback for maintaining a selected power. The actual temperatures aremeasured at temperature measurement device 102, and the temperatures aredisplayed at user interface and display 96. A control signal isgenerated by controller 98 that is proportional to the differencebetween an actual measured temperature, and a desired temperature. Thecontrol signal is used by power circuits 100 to adjust the power outputin an appropriate amount in order to maintain the desired temperaturedelivered at the respective sensor. A multiplexer can be included tomeasure current, voltage and temperature, at the numerous sensors 42,and energy can be delivered to RF electrodes 12 in monopolar or bipolarfashion.

Controller 98 can be a digital or analog controller, or a computer withsoftware. When controller 98 is a computer it can include a CPU coupledthrough a system bus. On this system can be a keyboard, a disk drive, orother non-volatile memory systems, a display, and other peripherals, asare known in the art. Also coupled to the bus is a program memory and adata memory.

User interface and display 96 includes operator controls and a display.Controller 98 can be coupled to imaging systems, including but notlimited to ultrasound, CT scanners, X-ray, MRI, mammographic X-ray andthe like. Further, direct visualization and tactile imaging can beutilized.

The output of current sensor 90 and voltage sensor 92 is used bycontroller 98 to maintain a selected power level at RF electrodes 12 aswell as adjust the amount of conductive medium to electrode 12 tomaintain a selected impedance level. The amount of RF energy deliveredcontrols the amount of power. A profile of power delivered can beincorporated in controller 98, and a preset amount of energy to bedelivered can also be profiled. Other sensors similar to sensors 90 and92 can be used by controller 98 for other ablation source deliverydevices 12 to maintain a controllable amount of an ablation energyand/or ablative agent.

Circuitry, software and feedback to controller 98 result in processcontrol, and the maintenance of the selected power that is independentof changes in voltage or current, and are used to change, (i) theselected power, (ii) the duty cycle (on-off and wattage), (iii) bipolaror monopolar energy delivery, and (iv) infusion medium delivery,including flow rate and pressure. These process variables are controlledand varied, while maintaining the desired delivery of power independentof changes in voltage or current, based on temperatures monitored atsensors 42.

Current sensor 90 and voltage sensor 92 are connected to the input of ananalog amplifier 104. Analog amplifier 104 can be a conventionaldifferential amplifier circuit for use with sensors 42. The output ofanalog amplifier 104 is sequentially connected by an analog multiplexer106 to the input of A/D converter 108. The output of analog amplifier104 is a voltage which represents the respective sensed temperatures.Digitized amplifier output voltages are supplied by A/D converter 108 tomicroprocessor 88. Microprocessor 88 may be a type 68HCII available fromMotorola. However, it will be appreciated that any suitablemicroprocessor or general purpose digital or analog computer can be usedto calculate impedance or temperature.

Microprocessor 88 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 88 corresponds to different temperatures andimpedances.

Calculated power and impedance values can be indicated on user interfaceand display 96. Alternatively, or in addition to the numericalindication of power or impedance, calculated impedance and power valuescan be compared by microprocessor 88 with power and impedance limits.When the values exceed predetermined power or impedance values, awarning can be given on user interface and display 96, and additionally,the delivery of RF energy can be reduced, modified or interrupted. Acontrol signal from microprocessor 88 can modify the power levelsupplied by energy source 40.

FIG. 18 illustrates a block diagram of a temperature/impedance feedbacksystem that can be used to control conductive medium flow rate throughcatheter 14. Electromagnetic energy is delivered to electrode 12 byenergy source 44, and applied to tissue. A monitor 110 ascertains tissueimpedance, based on the energy delivered to tissue, and compares themeasured impedance value to a set value. If the measured impedanceexceeds the set value a signal 112 is transmitted to conductive mediumsource in order to adjust the amount of conductive solution delivered toelectrode 12 and to maintain the impedance at a selected level. Ifmeasured impedance is within acceptable limits, conductive mediumcontinues to be applied to the tissue. During the application of energyto tissue sensor 42 measures the impedance of tissue and/or electrode12. A comparator 114 receives a signal representative of the measuredimpedance and compares this value to a pre-set signal representative ofthe desired impedance. Comparator 114 sends a signal to a flow regulator116 representing a need for a higher conductive medium flow rate, if thetissue impedance is too high, or to lower the flow rate if the measuredimpedance is at an acceptable level.

Referring now to FIG. 19, energy source 40 is coupled to electrode 12,to apply a biologically safe voltage to the selected tissue site.

Measuring circuits determine the root mean square (RMS) values ormagnitudes of the current and voltage. These values, represented asvoltages, are inputted to a diving circuit D to geometrically calculate,by dividing the RMS voltage value by the RMS current value, theimpedance of the tissue site at sensor 42.

The output voltage of the divider circuit D is presented at the positive(+) input terminal of comparator A. A voltage source V_(o) supplies avoltage across the variable resistor R_(v), thus allowing one tomanually adjust the voltage presented at the negative input ofcomparator A. This voltage represents a maximum impedance value beyondwhich power will not be applied to electrode 12.

The flow rate of conductive medium can be controlled based on the tissueimpedance. In one embodiment, the switch S is activated to allow theimpedance signal to enter the positive (+) input terminal of comparatorA. This signal along with the reference voltage applied to the negative(-) input terminal actuates comparator A to produce an output signal. Ifthe selected tissue ablation site is heated to a biologically damagingtemperature, the tissue impedance will exceed a selected impedance valueseen at the negative (-) input terminal, thereby generating a disablingsignal to disable energy source 40, ceasing the power supplied toelectrode 12.

The output signal of comparator A can be communicated to a pump coupledto the source of conductive medium. If the impedance of the selectedtissue ablation site is too high, despite the tissue impedance fallingwithin acceptable limits, the pump adjusts the rate of conductive mediumflow applied to electrode 12.

EXAMPLE 1

Ablation apparatus 10 was used to determine two-dimensional shrinkage ofa bovine. RF volumetric reduction was achieved using a single needleelectrode. Four miniature ultrasonic crystals were positioned to form asquare. Measurements were taken at control and post volumetric reductionat 15 watts initially with a 13% volumetric reduction, and 15 watts for4 hours with an additional 4% volumetric reduction. A total 17%volumetric reduction was achieved.

EXAMPLE 2

Ablation apparatus 10 was used to determine three-dimensional shrinkageof a bovine tongue. RF volumetric reduction was achieved with a singleneedle electrode with eight miniature ultrasonic crystals, creating acube. Application of 16 watts initially produced a 17% volumetricreduction of the tongue, 25 watts applied initially produced a 25%volumetric reduction, and 25 watts after hours produced an additional 4%reduction, for a total volumetric reduction of 29%.

EXAMPLE 3

A 35% volumetric reduction was achieved in porcine in vivo, with threedimensional gross at 20 watts initial application.

Referring now to FIG. 19, ablation volume dimensions were measured witha multidimensional digital sonomicrometry. An average decrease in the Zdirection was 20%, and volume shrinkage was 26%. Three-dimensionalshrinkage of tongue tissue due to m vivo RF ablation with the needle,ablation with 20 Watts) is presented in FIG. 20. Control volume beforeablation is compared with a post-ablation volume.

FIG. 20 illustrates two-dimensional shrinkage of a bovine tongue tissuedue to RF ablation with a needle electrode. The before and afterablation results are illustrated.

FIG. 21 illustrates in graph form ablation at 16 Watts resulted in a 17%volume shrinkage of the tissue in post-ablation verses control. Ablationat 25 watts resulted in a 25% volume shrinkage after ablation. Anadditional 4% area shrinkage was obtained after in long-term postablation (4 hours) verses post-ablation.

FIG. 22 illustrates a percent volume change after RF ablation. 16 Watts,ablation at 16 Watts for 20 minutes; 25 Watts, ablation at 25 Watts for20 minutes; 25 Watts (4 hours), and long tern post ablation (4 hoursafter 25 Watts ablation).

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

What is claimed is:
 1. An apparatus for ablating at least a portion ofan interior of a body structure, comprising:a catheter including acatheter interior and a port formed in a body structure of the catheter;an ablation energy delivery device at least partially positioned in thecatheter interior and configured to be advanced from the port into theinterior of the body structure to a selected tissue site and deliver anablation energy to the selected site, wherein the ablation energydelivery device is configured to be coupled to an ablation energysource; a sensor coupled to the ablation energy source, wherein thesensor is positionable in the interior of the body structure andmeasures an impedance of at least a portion of the selected tissue site;a conductive medium introduction member coupled to a source of aconductive medium and the catheter; a feedback control means coupled tothe sensor and the conductive medium source, wherein the feedbackcontrol means provides a controlled delivery of the conductive medium tothe selected tissue site in response to a level of measured impedance;and a cable coupled to the ablation energy delivery device.
 2. Theapparatus of claim 1, further comprising:an ablation energy deliverydevice advancement and retraction device at least partially positionedin the interior of the catheter.
 3. The apparatus of claim 1, whereinthe conductive medium introduction member is a lumen at least partiallypositioned in an interior of the catheter.
 4. The apparatus of claim 1,wherein the ablation energy delivery device includes an interior hollowlumen and an outflow port.
 5. The apparatus of claim 4, wherein theconductive medium introduction member is coupled to the ablation energydelivery device.
 6. The apparatus of claim 1, further comprising:acooling element including a cooling medium inlet conduit and a coolingmedium exit conduit both extending through an interior of the catheterforming at least a partial cooled catheter tissue interface surface,wherein the ablation energy delivery device has an ablation energydelivery surface that is thermally isolated from the cooling element. 7.The apparatus of claim 1, further comprising:an insulation sleevepositioned in a surrounding relationship to at least a portion of anexterior surface of the ablation energy delivery device.
 8. Theapparatus of claim 1, wherein the sensor is positioned at a distal endof the ablation energy delivery device.
 9. The apparatus of claim 7,wherein the sensor positioned at a distal end of the ablation energydelivery device and a second seninsulation sleeved at a distal end ofthe insulation sleeve.
 10. The apparatus of claim 1, wherein theablation energy delivery device is an RF electrode.
 11. The apparatus ofclaim 1, further comprising:a comparator device configured to compare ameasured impedance of a tissue site to a predetermined impedance valueand generate a signal representative of a difference between themeasured impedance and the predetermined impedance.
 12. The apparatus ofclaim 11, further comprising:a fluid control device for regulating arate of flow of the conductive medium through an ablation energydelivery device lumen in response to the signal from the comparatordevice.
 13. The apparatus of claim 1, further comprising:an energyoutput control device coupled to the energy source.
 14. The apparatus ofclaim 13, wherein the energy output control device comprises:animpedance measuring device for measuring an impedance value of tissuebased on an energy applied to the tissue; an impedance comparator devicefor comparing the measured impedance value of tissue to a predeterminedmaximum impedance value, the impedance comparing device generating adisabling signal if the measured impedance value exceeds thepredetermined maximum impedance value; and a communication device forcommunicating the disabling signal to the energy source to cease furtherdelivery of energy from the energy source to the ablation energydelivery device.
 15. A method for reducing a volume of a tongue,comprising:providing an ablation apparatus including a source ofablation energy, an ablation energy delivery device and a conductivemedium introduction member coupled to a source of a conductive medium;advancing at least a portion of the ablation energy delivery device intoan interior of the tongue; delivering a sufficient amount of energy fromthe energy delivery device into the interior of the tongue to debulk aselected section of the tongue without damaging a hypoglossal nerve;measuring an impedance of the selected section of the tongue; andintroducing the conductive medium to the selected section of the tongueto modify the impedance.
 16. The method of claim 15, wherein the energysource is an RF source and the ablation energy delivery device is an RFelectrode.
 17. The method of claim 15, wherein the energy source is acoherent source of light and the ablation energy delivery device is anoptical fiber.
 18. The method of claim 15, wherein the energy source isa heated fluid and the ablation energy delivery device is a catheterwith a closed channel configured to receive the heated fluid.
 19. Themethod of claim 15, wherein the energy source is a heated fluid and theablation energy delivery device is a catheter with an open channelconfigured to receive the heated fluid.
 20. The method of claim 15,wherein the energy source is a cooled fluid and the ablation energydelivery device is a catheter with a closed channel configured toreceive the cooled fluid.
 21. The method of claim 15, wherein the energysource is a cooled fluid and the ablation energy delivery device is acatheter with an open channel configured to receive the cooled fluid.22. The method of claim 15, wherein the energy source is a cryogenicfluid.
 23. The apparatus of claim 15, wherein the energy source is amicrowave source providing energy from 915 MHz to 2.45 GHz and theablation energy delivery device is a microwave antenna.
 24. Theapparatus of claim 15, wherein the energy source is an ultrasound sourceand the ablation energy delivery device is an ultrasound emitter. 25.The method of claim 15, wherein the energy source is a microwave source.26. The method of claim 15, wherein the electrode is advanced into aninterior of the tongue through a ventral surface of the tongue.
 27. Themethod of claim 15, wherein the ablation energy delivery device isadvanced into an interior of the tongue through an inferior dorsalsurface of the tongue.
 28. The method of claim 15, wherein the ablationenergy delivery device is advanced into an interior of the tonguethrough a dorsum surface of the tongue.
 29. The method of claim 15,wherein the ablation energy delivery device is advanced into an interiorof the tongue through a tip of the tongue.